Nitrogen dynamics in flooded soils, contamination of irrigation water, and yield of rice grains as a result of the applicaton of organic and chemical nitrogen fertilizers

Abstract

This study aimed to monitor the formation and mobility of mineral N in the soils and to evaluate the effect of these fertilizers on rice yield and contamination of water with ammonium and nitrate. The experiment was carried out in the field at Epagri Experiment Station in Itajaí, SC, southern Brazil, during the 2008/09 and 2009/10 crop seasons. Poultry liter was
applied in two forms: a) incorporated 30 days before sowing; b) on mudding, just before rice sowing. The urea was applied in two forms: a) urea in total dose incorporated on mudding just before sowing; b) urea split in three tmes (25, 50 and 80 days afer sowing). Also, we applied Entec 26® with half the dose incorporated on mudding and half 80 days afer sowing. The concentration of N-NH4+ in the soil reached high values in the frst weeks afer fertilizer applicaton and fell down 50 days afer sowing. The highest grain yield occurred in treatments with split urea and Entec 26® in the first season and with split urea and poultry liter in the last season. There was no contaminaton of the water by ammonium or nitrate. The early incorporation of nitrogen fertlizers tested is less efcient than split urea applicatons for the demand of N by rice plants.